Multilayer ceramic capacitor and semiconductor device

ABSTRACT

A multilayer ceramic capacitor includes a multilayer body including dielectric layers, first inner electrodes, and second inner electrodes stacked on one another, a first outer electrode electrically connected to the first inner electrodes, and a second outer electrode electrically connected to the second inner electrodes. The multilayer body includes first and second side surfaces respectively including first and second recesses where a midsection of each of the first and second side surfaces in a length direction is recessed inward in a width direction. When the multilayer ceramic capacitor is viewed in a stacking direction, a dimension of each of the first and second recesses in the length direction is smaller on an inner side than on an outer side in the width direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2020-068180 filed on Apr. 6, 2020. The entire contentsof this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a multilayer ceramic capacitor and asemiconductor device.

2. Description of the Related Art

A multilayer ceramic capacitor known in the art includes a multilayerbody and a pair of outer electrodes. The multilayer body has a layeredstructure in which dielectric layers and inner electrodes arealternately stacked on one another. Each outer electrode of the pair ofouter electrodes is disposed on a corresponding end surface of themultilayer body.

Such a multilayer ceramic capacitor is disclosed in U.S. Pat. No.9,263,186. Referring to FIG. 12 , multilayer ceramic capacitors 410 andsolder balls 420 are disposed on a substrate 400. The solder balls 420in FIG. 12 are arranged in a grid array on the substrate 400, which hasa rectangular shape. The multilayer ceramic capacitors 410 are disposedon the substrate 400 so as not to overlap the solder balls 420. Thesolder balls 420 may, for example, be needed to dissipate heat from thesubstrate 400 and to provide signal paths. For this reason, it is notpreferable to reduce the number of solder balls.

One of the multilayer ceramic capacitors 410 illustrated in FIG. 12 , ormore specifically, the multilayer ceramic capacitor 410 in themidsection is arranged obliquely to the edges of the substrate 400. Someof the solder balls 420 may not be optimally positioned in relation tothe multilayer ceramic capacitor 410 arranged obliquely to the edges ofthe substrate 400 and thus can come into contact with side surfaces ofthe multilayer ceramic capacitor 410.

Referring to FIG. 13 , a solder ball 420A is in contact with a sidesurface of a multilayer ceramic capacitor 410A, which is at the lowerright of the substrate 400. When the solder ball 420A in the moltenstate flows along a side surface of the multilayer ceramic capacitor410A including a pair of outer electrodes 411A, electrical continuitywill be established between the outer electrodes 411A, and consequently,a short circuit can occur.

As a workaround, the side surfaces of the multilayer ceramic capacitor410 may be recessed inward, which may be a practical approach toeliminate or reduce the possibility that some of the solder balls 420will come into contact with the side surfaces of the multilayer ceramiccapacitor 410.

Such a multilayer ceramic capacitor is disclosed in Japanese UnexaminedPatent Application Publication No. 2000-195741. Referring to FIG. 14 , amultilayer ceramic capacitor 140 has a pair of side surfaces 140 a,which each have a recess 150. The dielectric layers and the innerelectrodes are stacked on one another in a stacking direction T. Whenthe multilayer ceramic capacitor 140 in FIG. 14 is viewed in thestacking direction T, each recess 150 has a rectangular shape. Themultilayer ceramic capacitor 140 includes a pair of outer electrodes141, which face each other in a length direction L. The side surfaces140 a face each other in a width direction W. The stacking direction Tis orthogonal to the length direction L and the width direction W.

In the case that the multilayer ceramic capacitor 140 illustrated inFIG. 14 is disposed so as to be arranged obliquely to the edges of thesubstrate 400 illustrated in FIG. 12 , the recesses 150 in the sidesurfaces 140 a eliminate or reduce the possibility that some of thesolder balls 420 will come into contact with the side surfaces 140 a ofthe multilayer ceramic capacitor 140.

However, there is a downside to this. Forming the rectangular recesses150 in the respective side surfaces 140 a results in a reduction in thearea of overlaps between the inner electrodes separated by thedielectric layers, and the capacitance of the multilayer ceramiccapacitor 140 illustrated in FIG. 14 is reduced correspondingly.

SUMMARY OF THE INVENTION

In order to reduce or prevent a reduction in capacitance, preferredembodiments of the present invention provide multilayer ceramiccapacitors that each include side surfaces that are prevented fromcontacting solder balls on a substrate onto which the multilayer ceramiccapacitor is mounted, and semiconductor devices each including suchmultilayer ceramic capacitors.

A multilayer ceramic capacitor according to a preferred embodiment ofthe present invention includes a multilayer body, a first outerelectrode, and a second outer electrode. The multilayer body includesdielectric layers, first inner electrodes, and second inner electrodes.The dielectric layers and the first and second inner electrodes arestacked on one another. The multilayer body includes a first principalsurface, a second principal surface, a first side surface, a second sidesurface, a first end surface, and a second end surface. The firstprincipal surface is opposite the second principal surface in a stackingdirection in which the dielectric layers, the first inner electrodes,the second inner electrodes are stacked on one another. The first sidesurface is opposite the second side surface in a width directionorthogonal or substantially orthogonal to the stacking direction. Thefirst end surface is opposite the second end surface in a lengthdirection orthogonal or substantially orthogonal to both the stackingdirection and the width direction. The first outer electrode iselectrically connected to the first inner electrodes and located on thefirst end surface of the multilayer body. The second outer electrode iselectrically connected to the second inner electrodes and located on thesecond end surface of the multilayer body. The first side surfaceincludes a first recess where a midsection of the first side surface inthe length direction is recessed inward in the width direction. Thesecond side surface includes a second recess where a midsection of thesecond side surface in the length direction is recessed inward in thewidth direction. When the multilayer ceramic capacitor is viewed in thestacking direction, a dimension of each of the first recess and thesecond recess in the length direction is smaller on an inner side thanon an outer side in the width direction.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a multilayer ceramic capacitor accordingto a first preferred embodiment of the present invention.

FIG. 2 is a plan view of the multilayer ceramic capacitor in FIG. 1 ,illustrating the multilayer ceramic capacitor as seen in a stackingdirection.

FIG. 3 is a sectional view of the multilayer ceramic capacitor takenalong line in FIG. 1 .

FIG. 4 is a sectional view of the multilayer ceramic capacitor takenalong line IV-IV in FIG. 1 .

FIG. 5 is a plan view of the multilayer ceramic capacitor in FIG. 1 ,illustrating the multilayer ceramic capacitor as seen in the stackingdirection for the purpose of aiding in the explanation of a dimension ofa first recess and a dimension of a second recess according to apreferred embodiment of the present invention.

FIG. 6 is a plan view of a semiconductor device, schematicallyillustrating a structure in which the multilayer ceramic capacitorsaccording to the first preferred embodiment of the present invention aredisposed on a substrate.

FIG. 7 is provided to explain a non-limiting example of a method forproducing the multilayer ceramic capacitor according to the firstpreferred embodiment of the present invention, or more specifically, amethod for punching holes corresponding to first recesses and secondrecesses of multilayer ceramic capacitors through a mother multilayerbody.

FIGS. 8A and 8B are provided to explain a non-limiting example of amethod for producing multilayer chips by printing with a ceramic slurryand a conductive paste for forming inner electrodes.

FIG. 9 is a plan view of a multilayer ceramic capacitor according to asecond preferred embodiment of the present invention, illustrating themultilayer ceramic capacitor as seen in the stacking direction.

FIG. 10 is a plan view of the multilayer ceramic capacitor in FIG. 9 ,illustrating the multilayer ceramic capacitor as seen in the stackingdirection for the purpose of aiding in the explanation of dimension of afirst recess and the dimension of a second recess according to apreferred embodiment of the present invention.

FIG. 11 is a plan view of a multilayer ceramic capacitor according to athird preferred embodiment of the present invention, illustrating themultilayer ceramic capacitor as seen in the stacking direction.

FIG. 12 is a plan view of the structure disclosed in U.S. Pat. No.9,263,186, illustrating multilayer ceramic capacitors and solder ballsdisposed on a substrate.

FIG. 13 illustrates a state in which multilayer ceramic capacitors knownin the art and solder balls are disposed on a substrate, with one of thesolder balls being in contact with a side surface of one of themultilayer ceramic capacitors.

FIG. 14 is a perspective view of a multilayer ceramic capacitordisclosed in Japanese Unexamined Patent Application Publication No.2000-195741, illustrating the multilayer ceramic capacitor whose sidesurfaces have their respective rectangular recesses.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, features of the present invention will be described withreference to preferred embodiments of the present invention and thedrawings.

First Preferred Embodiment

FIG. 1 is a perspective view of a multilayer ceramic capacitor 10according to a first preferred embodiment of the present invention. FIG.2 is a plan view of the multilayer ceramic capacitor 10 in FIG. 1 ,illustrating the multilayer ceramic capacitor 10 as seen in a stackingdirection T. FIG. 3 is a sectional view of the multilayer ceramiccapacitor 10 taken along line III-III in FIG. 1 . FIG. 4 is a sectionalview of the multilayer ceramic capacitor 10 taken along line IV-IV inFIG. 1 .

The multilayer ceramic capacitor 10 includes a multilayer body 11, afirst outer electrode 20 a, and a second outer electrode 20 b. The firstouter electrode 20 a and the second outer electrode 20 b face each otheras illustrated in FIG. 1 .

A direction in which the first outer electrode 20 a and the second outerelectrode 20 b face each other is a length direction of the multilayerceramic capacitor 10 and is herein denoted by L. A direction in whichdielectric layers 12, inner electrodes 13 a, and inner electrodes 13 bare stacked on one another is herein referred to as a stacking directionand denoted by T. These layers and electrodes will be described later. Adirection orthogonal or substantially orthogonal to both the lengthdirection L and the stacking direction T is herein referred to as awidth direction and denoted by W. Any two of these directions (i.e., thelength direction L, the stacking direction T, and the width direction W)are orthogonal or substantially orthogonal to each other.

The multilayer body 11 includes a first end surface 15 a, a second endsurface 15 b, a first principal surface 16 a, a second principal surface16 b, a first side surface 17 a, and a second side surface 17 b. Thefirst end surface 15 a is opposite the second end surface 15 b in thelength direction L. The first principal surface 16 a is opposite thesecond principal surface 16 b in the stacking direction T. The firstside surface 17 a is opposite the second side surface 17 b in the widthdirection W.

Corners and ridges of the multilayer body 11 are preferably rounded.Each corner is where three surfaces of the multilayer body 11 meet. Eachridge is where two surfaces of the multilayer body 11 meet.

Referring to FIGS. 3 and 4 , the multilayer body 11 includes thedielectric layers 12, first inner electrodes 13 a, and second innerelectrodes 13 b, which are stacked on one another. More specifically,the multilayer body 11 has a layered structure in which the first innerelectrodes 13 a and the second inner electrodes 13 b are alternatelystacked and separated by the dielectric layers 12 in the stackingdirection T.

As illustrated in FIG. 4 , the dielectric layers 12 include outerdielectric layers 121, inner dielectric layers 122, and a margin 123. Inthe stacking direction T, the outer dielectric layers 121 are eachcloser to outer surfaces of the multilayer body 11 than the outermostinner electrode (the inner electrode 13 a or 13 b closer than the otherinner electrodes 13 a and 13 b to the outer surface in the stackingdirection T). The inner dielectric layers 122 are each disposed betweentwo inner electrodes (i.e., the inner electrodes 13 a and 13 b) adjacentto each other in the stacking direction T. When the multilayer body isviewed in the stacking direction T, none of the inner electrodes 13 aand 13 b is disposed in the margin 123.

More specifically, one of the outer dielectric layers 121 is disposedbetween the outermost inner electrode 13 a in the stacking direction Tand the first principal surface 16 a of the multilayer body 11, and theother outer dielectric layer 121 is disposed between the outermost innerelectrode 13 b and the second principal surface 16 b of the multilayerbody 11. Each of the inner dielectric layers 122 is disposed between thecorresponding first inner electrode 13 a and the corresponding secondinner electrode 13 b that are adjacent to each other in the stackingdirection T. The margin 123 is closer than the outer dielectric layers121 and the inner dielectric layers 122 to the outer surface in thewidth direction W.

The dielectric layers 12 are preferably made of a ceramic materialincluding, for example, BaTiO₃, CaTiO₃, SrTiO₃, SrZrO₃, or CaZrO₃ as aprincipal component. The ceramic material may include, in addition tothe principal component, minor amounts of an accessory component such asMn compounds, Fe compounds, Cr compounds, Co compounds, or Ni compounds,for example.

The first inner electrodes 13 a extend to the first end surface 15 a ofthe multilayer body 11. The second inner electrodes 13 b extend to thesecond end surface 15 b of the multilayer body 11.

The multilayer body 11 may include, in addition to the first innerelectrodes 13 a and the second inner electrodes 13 b, inner electrodesthat are not exposed at a surface of the multilayer body 11.

The first side surface 17 a of the multilayer body 11 includes a firstrecess 30 a, where the midsection of the first side surface 17 a in thelength direction L is recessed inward in the width direction W. Thesecond side surface 17 b of the multilayer body 11 includes a secondrecess 30 b, where the midsection of the second side surface 17 b in thelength direction L is recessed inward in the width direction W. Theserecesses will be described later. The first inner electrodes 13 a andthe second inner electrodes 13 b are recessed inward in the widthdirection W and have a shape corresponding to the first recess 30 a andthe second recess 30 b.

The first inner electrodes 13 a each include a facing electrode portionand an extended electrode portion. The facing electrode portion of eachfirst inner electrode 13 a faces the corresponding second innerelectrode 13 b. The extended electrode portion extends between thefacing electrode portion and the first end surface 15 a of themultilayer body 11. The second inner electrodes 13 b each include afacing electrode portion and an extended electrode portion. The facingelectrode portion of each second inner electrode 13 b faces thecorresponding first inner electrode 13 a. The extended electrode portionextends between the facing electrode portion and the second end surface15 b of the multilayer body 11.

The facing electrode portion of the first inner electrode 13 a and thefacing electrode portion of the second inner electrode 13 b face eachother with the dielectric layer 12 therebetween such that a capacitanceis generated, thus enabling the multilayer body to define and functionas a capacitor.

The first inner electrodes 13 a and the second inner electrodes 13 b maypreferably include a metal such as, for example, Ni, Cu, Ag, Pd, Pt, Fe,Ti, Cr, Sn, or Au or may include an alloy of these metals. The firstinner electrodes 13 a and the second inner electrodes 13 b may includethe same dielectric ceramic material as a dielectric ceramic materialincluded in the dielectric layers 12. In this case, the dielectricceramic content in the first inner electrodes 13 a and the second innerelectrodes 13 b may preferably be, for example, equal to or less thanabout 20 vol %.

It is not required that the inner electrodes 13 a and 13 b are made ofthe same material. Also, it is not required that each of the innerelectrodes 13 a and 13 b is made of the same material. Differentmaterials may be used for different portions of each inner electrode.

The first outer electrode 20 a is disposed on the first end surface 15 aof the multilayer body 11. The first outer electrode 20 a in the presentpreferred embodiment covers the entirety or substantially the entiretyof the first end surface 15 a of the multilayer body 11 and extends fromthe first end surface 15 a onto the first principal surface 16 a, thesecond principal surface 16 b, the first side surface 17 a, and thesecond side surface 17 b.

The second outer electrode 20 b is disposed on the second end surface 15b of the multilayer body 11. The second outer electrode 20 b in thepresent preferred embodiment covers the entirety or substantially theentirety of the second end surface 15 b of the multilayer body 11 andextends from the second end surface 15 b onto the first principalsurface 16 a, the second principal surface 16 b, the first side surface17 a, and the second side surface 17 b.

The first outer electrode 20 a and the second outer electrode 20 b mayeach include, for example, a base electrode layer and a plating layer onthe base electrode layer.

The base electrode layer may include, for example, a baked electrodelayer, a resin electrode layer, or a thin-film electrode layer, orvarying combinations of these layers, each of which will be describedlater. The base electrode layer may be made of the same ceramic materialas that of the dielectric layers 12 or a material similar to that of thedielectric layers 12 or may include glass, in which case the coefficientof linear expansion of the first outer electrode 20 a and the secondouter electrode 20 b may be close to the coefficient of linear expansionof the dielectric layers 12. In the case that the base electrode layerincludes the ceramic material described above or glass, the ceramicmaterial content or the glass content in the outer electrode ispreferably, for example, equal to or more than about 30 vol % and equalto or less than about 70 vol %.

The base electrode layer may include one or more baked electrode layers,each of which includes glass and metal, for example. The baked electrodelayer may include a metal such as, for example, Cu, Ni, Ag, Pd, Ti, Cr,or Au or may contain an alloy of these metals.

The baked electrode layer is obtained by baking a multilayer body coatedwith a conductive paste containing glass and metal.

The resin electrode layer may include conductive particles and athermosetting resin, for example. The resin electrode layer may beprovided directly on a ceramic raw material, in which case the bakedelectrode layer may be omitted. The base electrode layer may include oneor more resin electrode layers, for example.

The thin-film electrode layer is a deposit of metallic particles andpreferably has a thickness of, for example, not more than about 1 μm.The thin-film electrode layer may be formed by sputtering, vapordeposition, or any other known method for forming thin films.

The plating layer on the base electrode layer may include, for example,a metal such as Cu, Ni, Ag, Pd, Ti, Cr, or Au or may include an alloymade mainly of these metals. The base electrode layer may be overlaidwith one or more plating layers. The plating layer preferably has adouble-layer structure including a Ni plating layer and a Sn platinglayer, for example. The Ni plating layer protects the base electrodelayer from erosion by solder when the multilayer ceramic capacitor 10 ismounted. The Sn plating layer improves solder wettability needed formounting of the multilayer ceramic capacitor 10.

The first outer electrode 20 a and the second outer electrode 20 b mayeach be a plating layer disposed directly on the multilayer body 11, inwhich case the base electrode layer may be omitted.

The first side surface 17 a of the multilayer ceramic capacitor 10according to the first preferred embodiment includes the first recess 30a, where the midsection of the first side surface 17 a in the lengthdirection L is recessed inward in the width direction W. The second sidesurface 17 b of the multilayer ceramic capacitor 10 includes the secondrecess 30 b, where the midsection of the second side surface 17 b in thelength direction L is recessed inward in the width direction W.

When the multilayer ceramic capacitor 10 is viewed in the stackingdirection T, the dimension of each of the first recess 30 a and thesecond recess 30 b in the length direction L is smaller on an inner sidethan on an outer side in the width direction W. The first recess 30 a isdefined by surfaces 31 a, and the second recess 30 b is defined bysurfaces 31 b. In the present preferred embodiment, the surfaces 31 aand the surfaces 31 b are flat. When the multilayer ceramic capacitor 10is viewed in the stacking direction T, the surfaces 31 a extendobliquely from the first side surface 17 a toward the center of themultilayer body in the width direction W, and the surfaces 31 b extendobliquely and from the second side surface 17 b toward the center of themultilayer body in the width direction W. The dimension of each of thefirst recess 30 a and the second recess 30 b in the length direction Lis smaller on the inner side in the width direction W accordingly. Withthis structure, the first recess 30 a and the second recess 30 b as seenin the stacking direction T have a triangular or substantiallytriangular shape as illustrated in FIG. 2 .

The multilayer ceramic capacitor 10 may preferably be, for example,about 0.6 mm long (in the length direction L), about 0.3 mm wide (in thewidth direction W), and about 0.3 mm high (in the stacking direction T).The dimension of each of the inner dielectric layers 122 (the dielectriclayers 12 except for the outer dielectric layers and the margin) in thestacking direction T may preferably be, for example, equal to or morethan about 0.3 μm and equal to or less than about 3.0 μm, and morepreferably about 1.0 μm. The dimension of each of the first innerelectrodes 13 a and the second inner electrodes 13 b in the stackingdirection T may preferably be equal to or more than about 0.3 μm andequal to or less than about 3.0 μm, and more preferably about 0.7 μm.The dimension of the margin 123 in the width direction W, the dimensionof each of the extended electrode portions of the first inner electrodes13 a in the length direction L, and the dimension of each of theextended electrode portions of the second inner electrodes 13 b in thelength direction L may each preferably be, for example, equal to or morethan about 0.01 mm and equal to or less than about 0.1 mm, and morepreferably about 0.03 mm. The thickness of each of the first outerelectrode 20 a and the second outer electrode 20 b may preferably be,for example, equal to or more than about 3 μm and equal to or less thanabout 100 μm, and more preferably about 5 μm.

The dimension of the inner dielectric layers 122 in the stackingdirection T may be determined by the following procedure. The multilayerceramic capacitor 10 is ground such that the cross section passingthrough the midpoint of the multilayer ceramic capacitor 10 in thelength direction L and extending in both the stacking direction T andthe width direction W is exposed for observation under a scanningelectron microscope. Then, the thickness of the inner dielectric layer122 passing through the midpoint of the multilayer ceramic capacitor 10in the stacking direction T is measured on five lines extending in thestacking direction T on the exposed cross section. The middle line amongthe five lines is the center line that passes through the midpoint inthe width direction W. The five lines (the center line, two adjacentlines on one side in the width direction W, and two adjacent lines onthe other side in the width direction W) are equally or substantiallyequally spaced in the width direction W. The average of the fivemeasurement values obtained on the respective lines is taken as thedimension of each of the inner dielectric layers 122 in the stackingdirection T.

For more precise measurements, the multilayer body 11 may be dividedinto an upper portion, a middle portion, and a lower portion that arealigned in the stacking direction T. The upper portion, the middleportion, and the lower portion are subjected to measurements to obtainfive measurement values in each portion, and the average of theindividual measurement values is taken as the dimension of each of theinner dielectric layers 122 in the stacking direction T. The dimensionof each of the first inner electrodes 13 a in the stacking direction Tand the dimension of each of the second inner electrodes 13 b in thestacking direction T may be determined in the same or similar manner.

FIG. 5 is a plan view of the multilayer ceramic capacitor 10 in FIG. 1 ,illustrating the multilayer ceramic capacitor 10 as seen in the stackingdirection T for the purpose of aiding in the explanation of thedimension of the first recess 30 a and the dimension of the secondrecess 30 b according to the present preferred embodiment. Let L1 denotethe dimension of the multilayer ceramic capacitor 10 in the lengthdirection L, and let W1 denote the dimension of the multilayer ceramiccapacitor 10 in the width direction W. The maximum dimension of each ofthe first recess 30 a and the second recess 30 b in the length directionL is herein referred to as an indentation length and denoted by L2. Theratio of the indentation length L2 to the dimension L1 is preferably,for example, equal to or more than about 8.3% and equal to or less thanabout 83.4%, and more preferably about 16.7%.

The dimension of each of the first recess 30 a and the second recess 30b in the width direction W is referred to as indentation depth anddenoted by W2. The ratio of the indentation depth W2 to the dimension W1is preferably, for example, equal to or more than about 3.3% and lessthan about 50.0%, and more preferably about 16.7%.

The bottom of the first recess 30 a is denoted by 32 a, and the bottomof the second recess 30 b is denoted by 32 b. Let L3 denote thedimension of a portion of the multilayer ceramic capacitor 10 between anend in the length direction L and the bottoms 32 a and 32 b. The ratioof the dimension L3 to the dimension L1 may preferably be, for example,about 50%.

The dimension L1 of the multilayer ceramic capacitor 10 may preferablybe, for example, about 0.6 mm. The dimension W1 may preferably be, forexample, about 0.3 mm. The indentation length L2 is preferably, forexample, equal to or more than about 0.05 mm and equal to or less thanabout 0.5 mm, and more preferably about 0.1 mm. The indentation depth W2is preferably, for example, equal to or more than about 0.01 mm and lessthan about 0.15 mm, and more preferably about 0.05 mm. The dimension L3may preferably be, for example, about 0.3 mm.

The size of the multilayer ceramic capacitor 10 may be changed asrequired. For example, dimensions of the multilayer ceramic capacitor 10as expressed as “(the dimension in the length direction L, the dimensionin the width direction W, the dimension in the stacking direction T)”may be (about 5.7 mm, about 5.0 mm, about 5.0 mm), (about 4.5 mm, about3.2 mm, about 3.2 mm), (about 3.2 mm, about 1.6 mm, about 1.6 mm),(about 2.1 mm, about 1.2 mm, about 1.2 mm), (about 1.6 mm, about 0.8 mm,about 0.8 mm), (about 1.0 mm, about 0.5 mm, about 0.5 mm), or (about 0.4mm, about 0.2 mm, about 0.2 mm).

When the multilayer ceramic capacitor 10 according to the presentpreferred embodiment is viewed in the stacking direction T, thedimension of each of the first recess 30 a and the second recess 30 b inthe length direction L is, as described above, smaller on the inner sidethan on the outer side in the width direction W. When the multilayerceramic capacitor known in the art (i.e., the multilayer ceramiccapacitor disclosed in Japanese Unexamined Patent ApplicationPublication No. 2000-195741) is viewed in the stacking direction, itsrecesses have rectangular or substantially rectangular shapes and thedimension of each of the recesses in the length direction is constant onboth the inner side and the outer side in the width direction.

When the depth of each of the first recess 30 a and the second recess 30b (the dimension of each recess in the width direction) of themultilayer ceramic capacitor 10 according to the present preferredembodiment is equal to the depth of each recess of the multilayerceramic capacitor known in the art, each recess of the multilayerceramic capacitor 10 according to the present preferred embodiment issmaller than each recess of the multilayer ceramic capacitor known inthe art. This means that the capacitance of the multilayer ceramiccapacitor 10 according to the present preferred embodiment is greaterthan the capacitance of the multilayer ceramic capacitor disclosed inJapanese Unexamined Patent Application Publication No. 2000-195741.

The multilayer ceramic capacitor 10 according to the present preferredembodiment achieves the following advantage: the first recess 30 a inthe first side surface 17 a and the second recess 30 b in the secondside surface 17 b prevent the first side surface 17 a and the secondside surface 17 b from contacting solder balls disposed on a substrateonto which the multilayer ceramic capacitor 10 is mounted. When themultilayer ceramic capacitor 10 is viewed in the stacking direction T,the dimension of each of the first recess 30 a and the second recess 30b in the length direction L is smaller on the inner side than on theouter side in the width direction W. This structure reduces or preventsthe reduction in the capacitance of the capacitor.

The first inner electrodes 13 a and the second inner electrodes 13 b ofthe multilayer ceramic capacitor 10 according to the present preferredembodiment are recessed inward in the width direction W and have a shapecorresponding to the first recess 30 a and the second recess 30 b. Insuch a case, the area of each of the first inner electrodes 13 a and thesecond inner electrodes 13 b is greater than the area of each of theinner electrodes that have a rectangular or substantially rectangularshape, and the reduction in the capacitance of the capacitor will bereduced more effectively.

The multilayer ceramic capacitor known in the art includes rectangularor substantially rectangular recesses. When such multilayer ceramiccapacitors are conveyed on a conveyor belt, a multilayer ceramiccapacitor can partially get caught in a rectangular or substantiallyrectangular recess of another multilayer ceramic capacitor, such thatcracks will be produced. Consequently, these multilayer ceramiccapacitors will have poor yield rates. This is not the case with themultilayer ceramic capacitor 10 according to the present preferredembodiment. When the multilayer ceramic capacitor 10 is viewed in thestacking direction T, the dimension of each of the first recess 30 a andthe second recess 30 b in the length direction L is smaller on the innerside than on the outer side in the width direction W. This structurereduces or prevents the possibility that a multilayer ceramic capacitorconveyed on a conveyor belt will be partially caught in either of tworecesses (i.e., the first recess 30 a and the second recess 30 b) ofanother multilayer ceramic capacitor. The reduction in yield will bereduced or prevented accordingly.

The rectangular recesses of the multilayer ceramic capacitor known inthe art are each defined by three surfaces, which are formed by makingthree cuts in a multilayer ceramic capacitor in the process ofproduction. The first recess 30 a of the multilayer ceramic capacitor 10according to the present preferred embodiment is defined by twosurfaces, each of which is denoted by 31 a. The first recess 30 a maythus be formed by making only two cuts in a multilayer ceramic capacitorin the process of production.

FIG. 6 is a plan view of a semiconductor device 100, schematicallyillustrating a structure in which the multilayer ceramic capacitors 10according to the first preferred embodiment are disposed on a substrate40. The semiconductor device 100 includes the substrate 40, solder balls50 on the substrate 40, and the multilayer ceramic capacitors 10 on thesubstrate 40. As illustrated in FIG. 6 , the solder balls 50 are in agrid array on the substrate 40. The multilayer ceramic capacitors 10 donot overlap the solder balls 50 on the substrate 40.

Referring to FIG. 6 , the substrate 40 has a rectangular orsubstantially rectangular shape, and a few of the multilayer ceramiccapacitors 10 are oblique to the edges of the substrate 40. Some of thesolder balls 50 are immediately beside the multilayer ceramic capacitors10 that are oblique to the edges of the substrate 40 and are not incontact with the multilayer ceramic capacitors 10.

That is, the multilayer ceramic capacitors 10 according to the firstpreferred embodiment are disposed on the substrate 40 in such a manneras to avoid contact with the solder balls 50. This layout offers anadvantage that a larger number of solder balls may be disposed on thesubstrate. This layout thus enables the substrate 40 to achieve enhanceddissipation of heat and to provide a larger number of signal paths.

As an example of a practical application, the semiconductor device 100described above may be incorporated in a music player, a video player, anavigation apparatus, a communication apparatus, a mobile phone, asmartphone, a mobile information terminal, a tablet terminal, or anotebook computer, for example.

Method for Producing Multilayer Ceramic Capacitors

The following describes a non-limiting example of method for producingthe multilayer ceramic capacitors 10.

In the first production step, ceramic green sheets, a conductive pastefor forming inner electrodes, and a conductive paste for forming outerelectrodes are prepared. The ceramic green sheets to be used may, forexample, be well-known sheets and may each be obtained by coating a basematerial with a ceramic slurry including ceramic powder, resinoussubstances, and a solvent and by drying the ceramic slurry.

The ceramic slurry may include CaTi, ZrO₃, SrZrO₃, BaTiO₃, BaTi, orCaO₃, for example. The ceramic slurry may also, for example, resinoussubstances, each of which may be used as a dispersing agent or a binder.The concentration of solid matter in the ceramic slurry may preferablybe, for example, equal to or more than about 10 vol % and equal to orless than about 27 vol %. The pigment volume concentration (PVC) of theceramic powder, that is, the content of the ceramic powder in the totalsolid matter is preferably, for example, equal to or more than about 65%and equal to or less than about 95%.

The conductive paste for forming inner electrodes may include a metal,such as, for example, Ni, Cu, Ag, Pd, Pt, Fe, Ti, Cr, Sn, or Au, or aparticle size precursor of the metal, and a solvent. The conductivepaste for forming inner electrodes may also include, for exampleresinous substances, each of which may be used as a dispersing agent ora binder.

The viscosity of the paste for forming inner electrodes may preferablybe, for example, equal to or more than about 5 mPa·s and equal to orless than about 50 Pa·s. The concentration of solid matter in the pastefor forming inner electrodes may preferably be, for example, equal to ormore than about 9 vol % and equal to or less than about 20.5 vol %. ThePVC of the metal particles, that is, the content of metal particles inthe total solid matter is preferably, for example, equal to or more thanabout 70% and equal to or less than about 95%. The diameter of metalparticles may preferably be, for example, equal to or more than about 10nm and equal to or less than about 500 nm.

The inner electrodes are formed in the subsequent production step, inwhich the ceramic green sheets are printed with the paste for forminginner electrodes. The paste for forming inner electrodes is applied toform a shape having an inwardly recessed outline so that the shape ofthe inner electrodes corresponds to the first recess 30 a and the secondrecess 30 b.

Then, a mother multilayer body is produced by the following procedure. Apredetermined number of ceramic green sheets including no innerelectrode pattern formed thereon, ceramic green sheets including innerelectrode patterns formed thereon, and a predetermined number of ceramicgreen sheets including no inner electrodes formed thereon are stacked onone another in this order. The mother multilayer body is formed suchthat a plurality of multilayer ceramic capacitors 10 are obtained at thesame time from the multilayer body.

The mother multilayer body is then subjected to rigid pressing,isostatic pressing, or the like, for example. The mother multilayer bodymay be pressed at temperatures falling within the range of, for example,about 25° C. to about 200° C. The pressure applied to the mothermultilayer body may be, for example, equal to or more than about 1 MPaand equal to or less than about 200 MPa.

Then, holes are punched through the mother multilayer body by using apush cutter, a mechanical punch, or the like, for example, such that theholes correspond to the first recesses 30 a and the second recesses 30 bof the multilayer ceramic capacitors 10. The resultant state isillustrated in FIG. 7 , in which the mother multilayer body is denotedby 70, and the holes are denoted by 71. Subsequently, multilayer chipsare obtained by cutting the mother multilayer body 70 into apredetermined size with a dicing machine, laser beams, or the like, forexample. Referring to FIG. 7 , broken lines 72 denote lines along whichthe mother multilayer body 70 is cut. The cutting may be followed bybarrel polishing or the like, for example, in which case corners andridges of the multilayer chips are rounded.

Alternatively, the mother multilayer body 70 may be cut into apredetermined size when the holes corresponding to the first recesses 30a and the second recesses 30 b are punched. The simultaneous cutting andpunching may be accomplished by using, for example, a push cutter forcutting the mother multilayer body into pieces and punching the holescorresponding to the first recesses 30 a and the second recesses 30 b.

As another alternative, a printing apparatus such as, for example, a 3Dprinter may be used to produce multilayer chips. That is, printingtechniques may be used to produce multilayer chips, each of which isthen fired to obtain the multilayer body including the first recess 30 aand the second recess 30 b. Specifically, ceramic slurry 80 is appliedto form layers each having the shape illustrated in FIG. 8A, and aconductive paste 81 for forming inner electrodes is then applied on thetop layer to form a layer having the shape illustrated in FIG. 8B.Subsequently, the ceramic slurry 80 is applied thereon to form anotherlayer having the shape illustrated in FIG. 8B, and the conductive paste81 for forming inner electrodes is applied on the resultant layer toform still another layer having the shape illustrated in FIG. 8B. Theceramic slurry 80 is applied thereon to form a layer having the shapeillustrated in FIG. 8A, and the conductive paste 81 for forming innerelectrodes is applied on the resultant layer to form another layerhaving the shape illustrated in FIG. 8A. The ceramic slurry 80 and theconductive paste 81 for forming inner electrodes are alternately appliedin the same manner. After this printing process is iterated, the ceramicslurry 80 is applied on the outer side in the stacking direction to formlayers each having the shape illustrated in FIG. 8A. In this way,multilayer chips are produced.

A conductive paste for forming outer electrodes is then applied to themultilayer chips such that two end surfaces of each multilayer chip arecoated with the paste and two principal surfaces and two side surfacesof each multilayer chip are partially coated with the paste. Theconductive paste for forming outer electrodes may include, for example,a metal or a particle size precursor of the metal, and a solvent. Theconductive paste for forming outer electrodes may also include, forexample, resinous substances, each of which may be used as dispersingagent or a binder. The concentration of solid matter in the paste forforming outer electrodes may preferably be, for example, equal to ormore than about 9 vol % and equal to or less than about 20.5 vol %. ThePVC of the metal particles, that is, the content of metal particles inthe total solid matter is preferably, for example, equal to or more thanabout 70% and equal to or less than about 95%.

In the subsequent step, the multilayer chips are fired. The multilayerchips may be fired at temperatures falling within the range of about900° C. to about 1,300° C., for example. The firing temperature may bechanged to better suit the ceramic material or the conductive paste thatis used. In this way, a multilayer body and metal layers defining andfunctioning as outer electrodes are formed.

Alternatively, the multilayer chips may be fired before and after beingcoated with the paste for forming outer electrodes.

The metal layers may be finished by plating if appropriate. The metallayers may be plated with Ni and thereafter plated with Sn, for example.

These processes may be used in the production of the multilayer ceramiccapacitors 10.

Second Preferred Embodiment

FIG. 9 is a plan view of a multilayer ceramic capacitor 10A according toa second preferred embodiment of the present invention, illustrating themultilayer ceramic capacitor 10A as seen in the stacking direction T.The difference between the multilayer ceramic capacitor 10A according tothe second preferred embodiment and the multilayer ceramic capacitor 10according to the first preferred embodiment is in the shape of the firstrecess 30 a and the second recess 30 b.

There are some commonalities between the multilayer ceramic capacitor 10according to the first preferred embodiment and the multilayer ceramiccapacitor 10A according to the second preferred embodiment. The firstside surface 17 a of the multilayer body 11 includes the first recess 30a, where the midsection of the first side surface 17 a in the lengthdirection L is recessed inward in the width direction W, and the secondside surface 17 b of the multilayer body 11 includes the second recess30 b, where the midsection of the second side surface 17 b in the lengthdirection L is recessed inward in the width direction W. When themultilayer ceramic capacitor 10A is viewed in the stacking direction T,the dimension of each of the first recess 30 a and the second recess 30b in the length direction L is smaller on the inner side than on theouter side in the width direction W. As with the multilayer ceramiccapacitor 10 according to the first preferred embodiment, the multilayerceramic capacitor 10A according to the second preferred embodiment thusoffers the following advantage: the first recess 30 a in the first sidesurface 17 a and the second recess 30 b in the second side surface 17 bprevent the first side surface 17 a and the second side surface 17 bfrom contacting solder balls disposed on a substrate onto which themultilayer ceramic capacitor 10A is mounted, and this structure reducesor prevents the reduction in capacitance.

In the present preferred embodiment, the first recess 30 a and thesecond recess 30 b, respectively, are defined by a surface 31 a and asurface 31 b, which are each substantially arc-shaped when themultilayer ceramic capacitor 10A is viewed in the stacking direction T.The term arc herein refers to a circular arc, an elliptical arc, or anyother suitable shape defined by a curve.

FIG. 10 is a plan view of the multilayer ceramic capacitor 10A in FIG. 9, illustrating the multilayer ceramic capacitor 10A as seen in thestacking direction T for the purpose of aiding in the explanation of thedimension of the first recess 30 a and the dimension of the secondrecess 30 b according to a preferred embodiment. Let L1 denote thedimension of the multilayer ceramic capacitor 10A in the lengthdirection L, and let W1 denote the dimension of the multilayer ceramiccapacitor 10A in the width direction W. The dimension of each of thefirst recess 30 a and the second recess 30 b in the length direction Lis herein referred to as indentation length and denoted by L2. The ratioof the indentation length L2 to the dimension L1 is preferably, forexample, equal to or more than about 8.3% and equal to or less thanabout 83.4%, and more preferably about 38.3%. The dimension of each ofthe first recess 30 a and the second recess 30 b in the width directionW is herein referred to as indentation depth and denoted by W2. Theratio of the indentation depth W2 to the dimension W1 in the widthdirection is preferably, for example, equal to or more than about 3.3%and equal to or less than about 36.7%, and more preferably about 13.3%.The bottom of the first recess 30 a is denoted by 32 a, and the bottomof the second recess 30 b is denoted by 32 b. Let L3 denote thedimension of a portion of the multilayer ceramic capacitor 10A betweenan end in the length direction L and the bottoms 32 a and 32 b. Theratio of the dimension L3 to the dimension L1 may preferably be about50%, for example.

The dimension L1 of the multilayer ceramic capacitor 10A may preferablybe, for example, about 0.6 mm. The dimension W1 may preferably be, forexample, about 0.3 mm. The indentation length L2 is preferably, forexample, equal to or more than about 0.05 mm and equal to or less thanabout 0.5 mm, and more preferably about 0.23 mm. The indentation depthW2 is preferably, for example, equal to or more than about 0.01 mm andequal to or less than about 0.11 mm, and more preferably about 0.04 mm.The dimension L3 may preferably be, for example, about 0.3 mm.

In the multilayer ceramic capacitor 10 according to the first preferredembodiment, the two flat surfaces 31 a meet at the bottom 32 a of thefirst recess 30 a, and the two flat surfaces 31 b meet at the bottom 32b of the second recess 30 b. For this reason, cracks can be produced inthe bottom 32 a of the first recess 30 a and the bottom 32 b of thesecond recess 30 b. Alternatively, the bottoms 32 a and 32 b may besubstantially arc-shaped to reduce or prevent the possibility ofcracking.

In the multilayer ceramic capacitor 10A according to the secondpreferred embodiment, the surface 31 a defining the first recess 30 aand the surface 31 b defining the second recess 30 b are substantiallyarc-shaped. That is, the surfaces 31 a and 31 b are curved. Accordingly,the possibility of cracking is further reduced or prevented.

Third Preferred Embodiment

FIG. 11 is a plan view of a multilayer ceramic capacitor 10B accordingto a third preferred embodiment of the present invention, illustratingthe multilayer ceramic capacitor 10B as seen in the stacking directionT. The difference between the multilayer ceramic capacitor 10B accordingto the third preferred embodiment and the multilayer ceramic capacitor10 according to the first preferred embodiment is in the shape of thefirst recess 30 a and the second recess 30 b.

There are some commonalities between the multilayer ceramic capacitor 10according to the first preferred embodiment and the multilayer ceramiccapacitor 10B according to the third preferred embodiment. The firstside surface 17 a of the multilayer body 11 includes the first recess 30a, where the midsection of the first side surface 17 a in the lengthdirection L is recessed inward in the width direction W, and the secondside surface 17 b of the multilayer body 11 includes the second recess30 b, where the midsection of the second side surface 17 b in the lengthdirection L is recessed inward in the width direction W. When themultilayer ceramic capacitor 10B is viewed in the stacking direction T,the dimension of each of the first recess 30 a and the second recess 30b in the length direction L is smaller on the inner side than on theouter side in the width direction W. As with the multilayer ceramiccapacitor 10 according to the first preferred embodiment, the multilayerceramic capacitor 10B according to the third preferred embodiment thusoffers the following advantage: the first recess 30 a in the first sidesurface 17 a and the second recess 30 b in the second side surface 17 bprevent the first side surface 17 a and the second side surface 17 bfrom contacting solder balls disposed on a substrate onto which themultilayer ceramic capacitor 10B is mounted, and this structure reducesor prevents the reduction in capacitance.

When the multilayer ceramic capacitor 10B according to the presentpreferred embodiment is viewed in the stacking direction T, the firstrecess 30 a and the second recess 30 b have a trapezoidal orsubstantially trapezoidal shape. That is, the bottom 32 a of the firstrecess 30 a and the bottom 32 b of the second recess 30 b are flat.

The multilayer ceramic capacitor according to the present inventionoffers the following advantage: the first recess in the first sidesurface and the second recess in the second side surface prevent thefirst side surface and the second side surface from contacting solderballs disposed on a substrate onto which the multilayer ceramiccapacitor is mounted. When the multilayer ceramic capacitor is viewed inthe stacking direction, the dimension of each of the first recess andthe second recess in the length direction is smaller on the inner sidethan on the outer side in the width direction. This structure is moreeffective in reducing or preventing the reduction in the capacitance ofthe capacitor than the structure in which the dimension of each recessin the length direction is constant on both the inner side and the outerside in the width direction.

It should be noted that the present invention is not limited to thepreferred embodiments above and various applications and alterations arepossible within the scope of the present invention.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A multilayer ceramic capacitor comprising: amultilayer body including dielectric layers, first inner electrodes, andsecond inner electrodes, the dielectric layers and the first and secondinner electrodes being stacked on one another, the multilayer bodyincluding a first principal surface, a second principal surface, a firstside surface, a second side surface, a first end surface, and a secondend surface, the first principal surface being opposite the secondprincipal surface in a stacking direction in which the dielectriclayers, the first inner electrodes, the second inner electrodes arestacked on one another, the first side surface being opposite the secondside surface in a width direction orthogonal or substantially orthogonalto the stacking direction, the first end surface being opposite thesecond end surface in a length direction orthogonal or substantiallyorthogonal to both the stacking direction and the width direction; afirst outer electrode electrically connected to the first innerelectrodes and located on the first end surface of the multilayer body;and a second outer electrode electrically connected to the second innerelectrodes and located on the second end surface of the multilayer body;wherein the first side surface includes a first recess where amidsection of the first side surface in the length direction is recessedinward in the width direction; the second side surface includes a secondrecess where a midsection of the second side surface in the lengthdirection is recessed inward in the width direction; when the multilayerceramic capacitor is viewed in the stacking direction, a dimension ofeach of the first recess and the second recess in the length directionis smaller on an inner side than on an outer side in the widthdirection; and each of the first and second recesses has a trapezoidalor substantially trapezoidal shape when the multilayer ceramic capacitoris viewed in the stacking direction.
 2. The multilayer ceramic capacitoraccording to claim 1, wherein the first inner electrodes and the secondinner electrodes are recessed inward in the width direction and have ashape corresponding to the first and second recesses.
 3. A semiconductordevice comprising: a substrate; solder balls on the substrate; and themultilayer ceramic capacitor according to claim 1; wherein themultilayer ceramic capacitor is on the substrate.
 4. The semiconductordevice according to claim 3, wherein the semiconductor device isincluded in a music player, a video player, a navigation apparatus, acommunication apparatus, a mobile phone, a smartphone, a mobileinformation terminal, a tablet terminal, or a notebook computer.
 5. Thesemiconductor device according to claim 3, wherein the first innerelectrodes and the second inner electrodes are recessed inward in thewidth direction and have a shape corresponding to the first and secondrecesses.
 6. The multilayer ceramic capacitor according to claim 1,wherein each of the dielectric layers includes at least one of BaTiO₃,CaTiO₃, SrTiO₃, SrZrO₃, or CaZrO₃ as a principal component.
 7. Themultilayer ceramic capacitor according to claim 6, wherein each of thedielectric layers further includes at least one of a Mn compound, a Fecompound, a Cr compound, a Co compound, or a Ni compound as an accessorycomponent.
 8. The multilayer ceramic capacitor according to claim 1,wherein a ratio of a maximum dimension of each of the first and secondrecesses in the length direction to a dimension of the multilayerceramic capacitor in the length direction is equal to or more than about8.3% and equal to or less than about 83.4%.
 9. The multilayer ceramiccapacitor according to claim 1, wherein a maximum dimension of each ofthe first and second recesses in the width direction to a dimension ofthe multilayer ceramic capacitor in the width direction equal to or morethan about 3.3% and less than about 50.0%.
 10. The semiconductor deviceaccording to claim 3, wherein each of the dielectric layers includes atleast one of BaTiO₃, CaTiO₃, SrTiO₃, SrZrO₃, or CaZrO₃ as a principalcomponent.
 11. The semiconductor device according to claim 10, whereineach of the dielectric layers further includes at least one of as Mncompounds, Fe compounds, Cr compounds, Co compounds, or Ni compounds asan accessory component.
 12. The semiconductor device according to claim3, wherein a ratio of a maximum dimension of each of the first andsecond recesses in the length direction to a dimension of the multilayerceramic capacitor in the length direction is equal to or more than about8.3% and equal to or less than about 83.4%.
 13. The semiconductor deviceaccording to claim 3, wherein a maximum dimension of each of the firstand second recesses in the width direction to a dimension of themultilayer ceramic capacitor in the width direction equal to or morethan about 3.3% and less than about 50.0%.